For most of human history, people have been terrified by lightning. Frightening bolts from above, lightning was a tool of the gods to smite mortals for their hubris (or their unfortunate penchant for seeking shelter from ...

Helium atoms are loners. Only if they are cooled down to an extremely low temperature do they form a very weakly bound molecule. In so doing, they can keep a tremendous distance from each other thanks to the quantum-mechanical ...

Three major issues with Mexico's weak rule of law threaten to foil the successful implementation of the new reforms made possible when Mexico opened its energy sector to private and foreign investment in 2013, according to ...

Ground-breaking research from the University of Surrey and Augmented Optics Ltd., in collaboration with the University of Bristol, has developed potentially transformational technology which could revolutionise the capabilities ...

Successful trials of Chariot, a unique new system that simultaneously records temperature, humidity and energy use in the home, have opened the way for low-income households to save money while reducing risks to their health.

Researcher at TU Graz demonstrates in Nature Materials that it is possible to combine the high-energy density of batteries with the high-power output of super capacitors in a single system – thanks to liquid energy storage ...

For centuries, humans have dreamed of harnessing the power of the sun to energize our lives here on Earth. But we want to go beyond collecting solar energy, and one day generate our own from a mini-sun. If we're able to solve ...

Energy

In physics, energy (from the Greek ἐνέργεια - energeia, "activity, operation", from ἐνεργός - energos, "active, working") is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is subject to a conservation law. Different forms of energy include kinetic, potential, thermal, gravitational, sound, light, elastic, and electromagnetic energy. The forms of energy are often named after a related force.

Any form of energy can be transformed into another form, but the total energy always remains the same. This principle, the conservation of energy, was first postulated in the early 19th century, and applies to any isolated system. According to Noether's theorem, the conservation of energy is a consequence of the fact that the laws of physics do not change over time.

Although the total energy of a system does not change with time, its value may depend on the frame of reference. For example, a seated passenger in a moving airplane has zero kinetic energy relative to the airplane, but non-zero kinetic energy relative to the Earth.